Shareholders' Equity - Changes in Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
Tax benefit	$ 13	$ (21)	$ (73)	$ (69)
INCOME (LOSS) FROM CONTINUING OPERATIONS	(34)	88	248	255
Amount Reclassified from Accumulated Other Comprehensive Income | Employee Benefit Related Adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Prior service benefit	(9)	(9)	(27)	(26)
Actuarial losses	12	10	35	29
Total before tax	3	1	8	3
Tax benefit	0	0	0	0
INCOME (LOSS) FROM CONTINUING OPERATIONS	$ 3	$ 1	$ 8	$ 3